Secure communication systems are well known. They are often used when it is desirable to prevent the dissemination of sensitive information to unauthorized persons.
Intelligence-gathering organizations often employ cryptanalysts who attempt to decipher the encrypted or cipher text information transmitted in secure communication systems. Although finding the encryption key so that cipher text messages may be deciphered and interpreted is the ultimate goal, there are other techniques through which useful information may be extracted from encrypted transmissions without actually deciphering the message signals.
Traffic analysis is one technique employed to gather useful information from a secure communication channel without subjecting the message traffic to the rigorous cryptanalytic attack generally required to find the proper encryption key. For example, by noting the time of day during which peak traffic occurs, a cryptanalyst may derive meaningful information concerning the organizations among which communication is occurring. A sharp increase in the amount of secure traffic being transmitted among covert organizations may indicate that an important intelligence-gathering operation is about to commence. Similarly, monitoring enciphered transmissions among corporate entities may give a cryptanalyst some indication concerning imminent business transactions such as takeovers, mergers or other major financial dealings.
Accordingly, a need arises for a method of foiling traffic analysis information-gathering tools used by unauthorized listeners.